Feat: prevent modal close

[Creylay]

Summary

This PR improves user experience by preventing accidental modal closures in DashAI. Previously, modals would close automatically when users clicked outside them (backdrop click), causing data loss and frustration. Now modals only close through explicit user actions via close buttons.

Type of change

• Front end new feature.
• Bug fix.

Changes

• Disabled automatic modal closure on backdrop click for 13 critical modals
• Disabled ESC key closure (disableEscapeKeyDown)
• Added visible close buttons (X icon) in modal headers
• Implemented consistent Cancel/Save button patterns
• Applied responsive design for different screen sizes

How to Test

1. Open any modal (Dataset creation, New Experiment, Predictions, etc.)
2. Try clicking outside the modal - it should NOT close
3. Verify close button (X) works properly
4. Confirm Cancel/Save buttons function as expected

Notes

Affects 13 modals across the platform including DatasetModal, NewExperimentModal, PredictionModal, and explainer modals. This change prevents accidental data loss while maintaining full user control over modal interactions.